More insights from CPM and PDS. Charged and neutral defects in a-Si:H

CPM and PDS spectra of annealed and degraded a-Si:H are analyzed. Numerical simulations of CPM and PDS data using occupation statistics yield information on the energy distribution and the charge state of the defects. The simulations reveal the coexistence of charged and neutral defects resembling the predictions of the defect-pool model. Charged states dominate the defect densities of annealed and degraded a-Si:H. In the case of spatial homogeneous defect densities, different sensitivities of CPM and PDS on charged and neutral defects cause different defect absorptions detected by both methods. Spatially inhomogeneous defect densities caused, e.g. by voids or columnar growth are detected by combining CPM and PDS since PDS detects the total defect density while CPM favors regions with low defect densities.